Rolling filters of the general type to which the present invention relates have been used for many years in the filtration of gaseous medium, specifically air, but it has been impractical or uneconomical to use filter apparatus of this type in connection with the filtration of a liquid medium. The present invention provides a filter construction which permits the use of a rolling filter for filtering the flow of a liquid medium in a highly effective and efficient manner.
The filter media for liquid filtration have traditionally been a heavy layer of fibers or granular material which is in a form which can withstand the high pressure differentials which are normally associated with the filtration of a liquid flow. Such filter media are not conducive to use in a rolling filter. The normal liquid filtration apparatus utilizes backwashing or similar techniques which require interruption of the flow of the liquid through the filter chamber. If an uninterrupted flow is required, parallel filtration chambers are provided which permit diversion of the flow from one chamber to the next during backwashing or regeneration.
Gas filtration, on the other hand, has used a filter medium which is readily incorporated into a rolling filter and which therefore is effective and economical, particularly if modified as in my earlier Patent Application. However, until the present invention, there has not been any rolling filter apparatus which is effective and economical for use for filtration of flowing liquids.